ABSTRACT Support is requested for a Keystone Symposia conference entitled Progress and Pathways Toward an Effective HIV Vaccine, organized by Drs. M. Juliana McElrath, Pamela J. Bjorkman and Beatrice H. Hahn. The conference will be held from January 28-February 1, 2018 in Banff, Alberta. After three decades, HIV-1 continues to afflict and kill millions of people worldwide. A safe and effective vaccine that elicits potent and durable protective immunity has the greatest prospect to end the AIDS epidemic. Development of an HIV vaccine has proven scientifically challenging, as evidenced by only one weakly efficacious regimen after evaluation of four distinct regimens. However, the field is in a phase of rapid growth and innovation for new vaccine strategies that hold promise for efficacy. Such emerging, novel findings will be the focus of this meeting and will include: 1) Technological advances in structural properties of the HIV-1 envelope glycoprotein and its recognition and interactions with potent neutralizing antibodies, 2) Improved animal model platforms that can better mimic the transmitted founder HIV-1 strains and human immune recognition; 3) Greater understanding of host B and T cell immunobiology in the lymphoid germinal centers that is critical to optimize candidate vaccines and immunization regimens; 4) New tools for interrogating human immune repertoire; and 5) Highlights of promising strategies in first-in-human to efficacy studies. Emphasis will be placed on unpublished findings and advances specifically relevant to human immunology and HIV vaccine targets.